You'll get about a million different, completely valid answers to this question, and most of them will inadvertently revolve around one question: How often do you plan on riding?
The core difference as far as beginner/advanced is concerned between a "soft" and "stiff" board is how much strength it requires to keep you upright when you don't have the right pressure on the board. In other words, when you make a mistake on a soft board, it's less likely to cost you your face. A soft board will kind of just go with the flow of the terrain on its own, a stiff board will require you to have the strength to keep it on track, in return, the stiff board will be more responsive and more capable of handling difficult terrain. If you go out once every two weeks or less, you will be very unlikely to develop the strength to take advantage of a stiffer board. So, if you plan on hitting the slopes at least once a week, feel free to go with a mid-stiff or very stiff board, as those will scale with you as you get better.
EDIT: regarding the custom flying V. It would definitely cause you some growing pains for the first several days you were on it, but your body will catch on pretty quickly, so long as you stay on top of riding frequently. Otherwise, if your strength and technique never catch up to what the board demands, it'll make for some really sad boarding trips. So as usual, it revolves around the question of ride time!
Last edited by Irahi; 05-23-2011 at 05:19 PM.